Cold-induced thermogenesis, or the increase in energy expenditure upon cold exposure, indicates metabolic stress, as such, cold-induced thermogenesis may signal an appropriate stimulus to improve metabolic health. Cold acclimation may alter cold-induced thermogenesis due to changes in (non)shivering thermogenesis and blood flow. The main aim of this research is to compare the energy expenditure responses, during a standardised cold stress (~ 9°C air temperature, maximum 1 hour), of Siberian adults with Western European adults. The subjects will be individually matched for age, sex, body mass and height. It was hypothesised that cold-induced thermogenesis will be reduced in the Siberian population.

Inclusion Criteria:

• Signed informed consent
• Western European origin or of Siberian origin
• BMI between 18.5 and 35 kg/m2
• Generally healthy (determined by dependent physician)

Exclusion Criteria:

• Smoking
• Active, uncontrolled cardiovascular disease or cancer
• Raynaud's disease
• Participation in another biomedical study within 1 month before the first study
• Cold-acclimated (Western European group), such as takes daily extended cold baths, works in a refrigerated environment, or regular cold-water swimming within 1 month of starting the study
• Medication use known to hamper subject's safety during study procedures
• Abuse of alcohol or drugs